[CentOS] raid1 disk format?

Tue Jun 10 16:59:32 UTC 2008
Ross S. W. Walker <rwalker at medallion.com>

Les Mikesell wrote:

> If you have a disk with several partitions set up as members of a raid1 
> md devices, can you make a dd image of that disk to replace its matching 
> drive with identical partitions or are there differences between the 
> mirrored partitions?

you can 'dd' the MBR and then re-add the partitions to the raid for
resyncing with 'mdadm'.

# dd if=/dev/sda of=/dev/sdb bs=512 count=1
# mdadm /dev/md0 --add /dev/sdb1
# mdadm /dev/md1 --add /dev/sdb2

If you want to really make sure you got everything you could dd the
whole first track with:

# dd if=/dev/sda of=/dev/sdb bs=512 count=63

-Ross

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